I have built a couple floating beds now and assembly and disassembly is very time consuming. I've tried researching possible braces to allow the person who is assembling the frame the quickly connect/disconnect the middle braces. Currently the middle 2x4 boards are screwed into to outer frame.
The boards need to be completely secured due to the fact that the top frame is sitting on top of a smaller frame so it appears to be floating.
In my mind I've always pictured a 2x4 connector that you slide the board into and then close the top so you can't pull it back up. It would have one on each side of the each middle support braces. I just can't find anything similar with my research.